Lower genital tract infections, including sexually transmitted diseases (STDs) are some of the most common clinical problems among women of childbearing age. Vaginal discharge can be due to vaginal infections (yeast, bacteria, and trichomonas) or cervical infections (gonorrhea or chlamydia). Additionally, there is a body of evidence linking vaginal infections to preterm delivery, low birth weight, and neonatal mortality. Bacterial vaginosis is one of the most common genital infections in pregnancy. Women with bacterial vaginosis diagnosed during the second trimester of pregnancy are 40 percent more likely to give birth to a premature, low-birth weight infant than women without bacterial vaginosis. The prevention of even a small proportion of such births could translate into large monetary savings and a decrease in neonatal morbidity and mortality.
Lactobacilli are Gram positive rods that are a part of the microbial flora of the human mouth, gut, and vagina. Vaginal lactobacilli are thought to play an important role in resistance to infection via production of lactic acid and acidification of the vagina or by production of other antimicrobial products, such as hydrogen peroxide (H2O2). It has been demonstrated that women with predominant vaginal Lactobacillus flora have a 50% lower frequency of gonorrhea, chlamydial infections, trichomoniasis and bacterial vaginosis. The presence of H2O2-producing lactobacilli in the vagina have been linked to a decreased frequency of bacterial vaginosis, yeast vaginitis and sexually transmitted pathogens including Neisseria gonorrhea, Chlamydia trachomatis, and Trichomonas vaginalis. In vitro studies have demonstrated that H2O2-producing lactobacilli have potent bactericidal and viricidal properties against vaginal pathogens and even against human immunodeficiency virus (HIV) (see, e.g., Sha et al. (2005) J Infect Dis 191:25-32; Martin et al. (1999) J Infect Dis 180:1863-68).
Many women of childbearing age lack vaginal lactobacilli. The vaginal ecosystem is dynamically affected by medications, general health status, sexual practices, and contraception. Many vaginal and systemic medications may kill vaginal lactobacilli. Hence, treatment of sexually transmitted diseases with antibiotics may place women at increased risk for repeated acquisition of the diseases. These findings, along with the widespread belief that lactobacilli generally promote vaginal health, suggest that women should recolonize the vagina with Lactobacillus to prevent or treat genital tract infections.
Lactobacillus products for intravaginal or oral use have been available for over 100 years in the form of “acidophilus” preparations available in health food stores, and acidophilus milk or yoghurt bought in grocery stores (from Lactobacillus acidophilus). These products have included vaginal suppositories containing lyophilized Lactobacillus acidophilus or other Lactobacillus species of human origin as well as various nutritional supplements. These products have been largely non-efficacious due to the failure of the products to colonize the vagina with the exogenous lactobacilli, likely due to the poor quality of the commercially available products or the use of ecologically inappropriate strains. Lactobacillus food products or supplements are often contaminated with other potential pathogens. In addition, Lactobacillus obtained from yoghurt is often unable to bind to vaginal epithelial cells. Binding of lactobacilli to the mucosal surface is a necessary step to establish colonization of the host organism. Thus, commercially available Lactobacillus products generally have little utility in prevention or treatment of vaginal infection because the products contain inappropriate microbe strains, are contaminated with other potentially pathogenic organisms, have low viability, and/or do not have the ability to bind to vaginal mucosa and establish colonization.